There is an ongoing need to develop and optimize polymeric materials for a wide range of applications. Various polymer characterization techniques have been developed to determine the properties and compositions of such polymeric materials, allowing researchers to better assess their next step in obtaining useful polymeric materials. For example, gel permeation chromatography (GPC) is one type of size exclusion chromatography (SEC) that is commonly employed to assess the molecular mass and molecular mass distributions of polymers. Differential scanning calorimetry (DSC) is a technique used to study the thermal transitions such as the glass transition that a polymer experiences as its temperature changes. There are many other techniques known in the art for evaluating the performance of polymeric materials such as rheology measuring techniques and light scattering techniques.
Reference standards are required to calibrate or test the instruments employed for such polymer characterization techniques. The most useful reference standards for calibrating instruments such as gas permeation chromatographs have relatively narrow molecular-weight distributions. Unfortunately, minimizing the molecular weight distribution of polyethylene, which is one of the most widely used polymers, has proven to be very difficult. The lack of good polyethylene reference standards limits the ability of researchers to accurately determine the properties of polymeric materials.
A need therefore exits to develop polymer fractions, for example polyolefin fractions and more specifically polyethylene fractions, that would serve as good reference standards for polymer characterization instruments. In particular, it is desirable to develop polyethylene fractions having narrower molecular weight distributions.